The invention relates to a communications network for exchanging data packets of ATM connections, a method for making available connection data, a method for determining path information, a network node for a lower network level, and a network node for a higher network level.
A communications network of the type to which the present invention is directed is currently associated with the designation PNNI. A frequently found version of this abbreviation is “private network network interface”. However, the use of such networks is now in no way limited to private networks. An important application of such networks is in the context of the Internet.
Such a communications network is generally physically identical to a part of the global communications network via which for example telephone calls are also conducted; however it may be logically distinct therefrom.
In such a communications network, data are transferred in the form of packets, a packet head of each data packet containing an item of path information with the aid of which it is routed through the communications network. This path information is acquired in a source network node from the destination information relating to a destination network node. The source network node is the network node at which the particular data packet enters this communications network, while the destination network node is the network node at which the particular data packet exits from the communications network. The path information must clearly define a path so that data packets with the same path information must also take the same path. However, the path information need not necessarily contain, in each sub-section of the path, all the detailed information for the entire path, but can be redefined en route for the particular next larger section.
In order always to be able to define the path information for the entire path actually in the source network node, every network node which can constitute a source network node must be able to access the connection data for the whole of the communications network. In known communications networks of this kind, this occurs in that each network node of the lowest network level contains a data bank in which connection data for the whole of the communications network are stored. The larger such a communications network becomes, the larger each individual data bank must be; the maintenance of the data is also problematic.